Kawasaki's Kelly Smith took the $1,500 Progressive Direct Holeshot Award to begin the 20-lap main event in front, with injured championship leader Chad Reed taking the advantage later on in the lap.

The Australian held his position until lap four, when he lost momentum in the whoops section - allowing Windham to pass. Reed stayed close to the Honda rider until lap 9, after which Windham pulled steadily away, while Reed held on to comfortable second place ahead of Andrea Short.

"Tonight I just wanted to put myself into a good position," said Windham, who is now 13 points behind Reed with two rounds to go. "[Chad] put himself in a good position to not lose too many points tonight. It's all about me now and I feel good about the ride I put in tonight. I'm giving it all I can and that alone feels good."

"Man I glad that's over!" Reed admitted. "Tonight's race was a true test of the treatment I've been receiving all week and although we thought it was working I knew I wouldn't know for sure until I got out there for the race.

"I really pleased with the progress we have made in the seven days since the crash.

"My shoulder's definitely a lot better than last weekend. I just couldn't make it happen in the whoops. I didn't want to lay [the bike] down, so I rode for second tonight. I want this title and I'm not about to let it go. I feel like I've let these guys into this points' battle all season long by making mistakes.

"I looking forward to making amends on those mistakes over the next two races," Reed added.

Reed will resume treatment for his shoulder over then next few days before preparing for the penultimate round of the championship at Seattle's Qwest Field on Saturday 26th April.

Meanwhile, a clash between title rivals Trey Canard and Ryan Villopoto saw the former clinch his first-ever AMA Supercross Lites championship, with a win, in St Louis.

Canard held a three-point lead heading into the series finale and grabbed the Progressive Direct Holeshot Award at the start of the main event, with Monster Energy/Pro Circuit/Kawasaki star Villopoto in third place.

Villopoto's team-mate Branden Jesseman then took over the lead on the opening lap, with Canard and Villopoto settling into second and third, respectively.

The win and the championship would ultimately be decided at the end of lap four as both Villopoto and Canard overtook Jesseman.

With Villopoto leading, Canard dived for the inside and made contact with Villopoto, sending the multiple Lites champion off the track.

Canard kept his balance and took over sole possession of the lead and walked away with the first professional AMA championship of his career.

"I really didn't mean to take him out," claimed Canard, a four-time winner on the season. "I think that's racing and I would expect him to do the same to me if it came down to this last race. I really wanted this championship since I was like three years old. I just trained hard all week long and I can't thank my team enough for getting this championship."

Jesseman finished second while Canard's Torco Fuels Honda team-mate Josh Grant was third.

AMA Supercross Class Results, St. Louis
1. Kevin Windham, Centreville, Miss., Honda
2. Chad Reed, Tampa, Fla., Yamaha
3. Andrew Short, Smithville, Texas, Honda
4. Nathan Ramsey, Menifee, Calif., Yamaha
5. Thomas Hahn, Decatur, Texas, Kawasaki
6. Davi Millsaps, Cairo, Ga., Honda
7. Justin Brayton, Murrieta, Calif., KTM
8. Paul Carpenter, Ithaca, N.Y., Honda
9. Travis Preston, Hesperia, Calif., Kawasaki
10. Jason Thomas, Melrose, Fla., Honda

AMA Supercross Class Season Standings:
1. Chad Reed, Tampa, Fla., Yamaha, 318
2. Kevin Windham, Centreville, Miss., Honda, 305
3. Davi Millsaps, Cairo, Ga., Honda, 244
4. Andrew Short, Smithville, Texas, Honda, 241
5. Joshua Hill, Yoncalla, Ore., Yamaha, 196
6. Tim Ferry, Largo, Fla., Kawasaki, 190
7. Nathan Ramsey, Menifee, Calif., Yamaha, 173
8. David Vuillemin, Murrieta, Calif., Suzuki, 146
9. Paul Carpenter, Ithaca, N.Y., Honda, 136
10. Nick Wey, Dewitt, Mich., KTM, 131
AMA Supercross Lites Class Results, St. Louis
1. Trey Canard, Elk City, Okla., Honda
2. Branden Jesseman, New Brighton, Pa., Kawasaki
3. Josh Grant, Riverside, Calif., Honda, 71
4. Ryan Villopoto, Poulsbo, Wash., Kawasaki
5. Ryan Morais, Murrieta, Calif., Yamaha
6. Kyle Chisholm, Seminole, Fla., Kawasaki
7. Ryan Sipes, Vine Grove, Ken., KTM, 70
8. Nico Izzi, Saint Clair., Mich., Suzuki
9. Matt Goerke, Lake Helen, Fla., KTM
10. Billy Payne, Simi Valley, Calif., Honda, 60
Eastern Regional AMA Supercross Lites Class Season Standings:
1. Trey Canard, Elk City, Okla., Honda, 147
2. Ryan Villopoto, Poulsbo, Wash., Kawasaki, 137
3. Nico Izzi, Saint Clair., Mich., Suzuki, 99
4. Branden Jesseman, New Brighton, Pa., Kawasaki, 94
5. Josh Grant, Riverside, Calif., Honda, 91
6. Tyler Bowers, Danville, Ken., Yamaha, 86
7. Ryan Morais, Murrieta, Calif., Yamaha, 84
8. Ryan Sipes, Vine Grove, Ken., KTM, 84
9. Martin Davalos, Cairo, Ga., KTM, 73
10. Billy Payne, Simi Valley, Calif., Honda, 71